The invention relates to a device for the location of golf balls comprising a transmitter unit which is arranged in the golf ball which can be actuated by means of a control unit and which transmits electromagnetic locating signals and an associated electrical storage capacitor which is likewise accommodated in the golf ball and serves as the energy store, with the storage capacitor being rechargeable for a temporally restricted operating period by means of an energy receiver arranged in the golf ball and by means of an external energy transmitter, and further comprising a portable or mobile signal receiving unit which responds to the locating signal and also an associated evaluating circuit for generating directionally dependent signals for the localization of the golf ball.
A corresponding device is known from WO-A 89/02 768. A lost golf ball can be found again in principle with this device, however account is not taken of the fact that the search for a golf ball can be made more difficult by the location signals of other golf balls. Account must namely be taken of the fact that golf balls lost by relatively many players will simply be left lying on the terrain even with the availability of a corresponding search device for locating the lost ball. This will lead to a relatively large number of balls always being present in the terrain which transmit location signals with reducing intensity corresponding to the remaining residual capacity of the energy store which supplies the transmitter units of the balls, and this can cause considerable disturbance when searching for a freshly lost ball.
Similar problems occur with devices in accordance with GB-A 11 72 449. In accordance with this document the transmitter unit arranged in the ball can be formed as a reflector for high frequency signals which are generated in an external detector which then receives the signals reflected back by the ball-side reflector and evaluates them to locate the golf ball. The ball-side transmitter unit is thus formed as a passive transmitter which draws its operating energy from a high frequency field. A similar system is also described in German utility model 87 09 503. Here the ball-side reflectors each consist of a two part foil antenna with a Varactor diode connected between their inner ends, with the Varactor diode bringing about a frequency doubling of the reflected high frequency signal. All such systems in which the golf ball contains a passive transmitter have however, the disadvantage that a lost golf ball which is left lying on the golf course, i.e. is forgotten or not sought, will at once again become active in transmission when a detector is set into operation. In this way the finding of a further lost golf ball can be made impossible or very difficult.
In GB-A 11 72 449 it is indeed proposed to provide golf balls with radioactive material the half life of which far exceeds the normal life of a golf ball. Such golf balls can admittedly be located in principle with detectors which respond to radioactive radiation, however the searching of a specific golf ball is made considerably more difficult through further golf balls lying in terrain since all lost balls are radioactive in a basically similar manner.
Accordingly it is the object of the invention to provide an arrangement for finding specific individual golf balls while precluding as far as possible sources of disturbance caused by other golf balls.
This and other objects are satisfied in accordance with the invention in an apparatus of the initially named kind in that the energy store is provided as the operating voltage source of a constant current source which supplies the transmitter unit of the golf ball and also of a control unit which actuates the transmitter unit, with the energy store having a capacity which is dimensioned for a temporally restricted operating period of the control unit and/or of the transmitter unit.
In the system of the invention it is ensured through the constant current source that the ball-side transmitter unit generates locating signals with constant intensity during the transmitter operation. At the same time the transmitter operation is restricted timewise since the transmitter unit can only operate as long as the residual capacity of the energy store is sufficient to operate the control unit or the constant current source. In this manner it is possible to reliably prevent the transmitter unit being able to transmit disturbing signals over a longer period of time with reducing intensity in accordance with the residual capacity of the energy store.
After the termination of the transmission operation of the transmitter unit of a golf ball, renewed operation is only then possible when the golf ball has been found and recharged. In this way it can be reliably ensured that the localization of another golf ball is not hindered in undesirable manner.
In accordance with a further preferred embodiment of the invention the transmitter unit is controlled by a control unit, connected to the energy store in such a way that the transmitter unit generates periodic transmission signals. In consequence of this such a device has only a small current requirement so that the energy store also only needs to be dimensioned for a small current requirement.
This kind of a control unit is realized in a particularly preferred embodiment of the invention in that it includes an astable flip-flop and a subsequent differentiation stage, whereby a rectangular waveform signal generated by the astable flip-flop is supplied to the differentiator stage and a transistor switch which is provided for pulsed operation of the transmitter unit is controlled by the output signal of the differentiator stage. In this way a simple circuit needed for the pulsed operation is obtained.
In order to simultaneously locate several golf balls, provision is made in a particularly preferred embodiment of the invention for the transmitter units to have a certain number of transmission frequencies, with one of these transmission frequencies being associated in each case with groups of golf balls formed at the manufacturer in such a way that the transmitter units of the golf balls belonging to a group each transmit at the same frequency, and furthermore each golf ball has a code for the identification of the transmission frequency. For this purpose the reception frequencies of the signal receiving units are adjustable to these transmission frequencies.
Furthermore, for the simultaneous location of several golf balls, a further advantageous embodiment of the invention results in that the charging signals of the energy transmitter are coded and different transmission frequencies of the transmitter unit can be set through this coding, with the reception frequency of the signal receiving unit being in each case tunable thereto. A further development of this embodiment consists in that a microprocessor is provided at the transmitter unit for decoding the coded charging signals and for setting the transmission frequency; and in that this microprocessor controls a decoder, a programmable frequency divider and a PLL (phase-locked loop) circuit.
For the rapid finding of a golf ball the output signal of the evaluation circuit represents, a signal which is dependent on the field strength of the transmitted signal, with the value of this field strength depending on the orientation of an antenna associated with the signal receiving unit and its distance from the golf ball to be sought.
For the better determination of the directional characteristic of the transmission signal, the signal receiving unit can in particular be equipped in accordance with another advantageous development of the invention with a multiple antenna diversity system, wherein, in accordance with a further development of this embodiment, the display unit sets forth the direction in which the golf ball to be sought is located independently of the orientation of the antennas.
Furthermore, the display unit is so laid out in a favorable embodiment of the invention that it transmits optical and/or acoustical signals.
In a particularly advantageous further development of the invention, the energy store is a capacitor.
Finally, in a particularly advantageous embodiment of the invention the signal receiving unit, the charging circuit and the charging device are arranged in a portable housing, with the golf ball containing the transmitter unit with the energy receiver and the energy store and optionally the control unit; and in that the charging device is formed as a charging golf bag for the receiving of the golf balls.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.